Recently, highly dense mounting has been implemented in mounting of a camera module, and a flexible printed board (hereinafter, also referred to as an FPC) has been frequently used as a member on which the camera module is mounted. The FPC normally has a variable portion and a fixed portion and the camera module is mounted on the fixed portion in many cases.
When the fixed portion on which the camera module is mounted is warped, a sensor included in the camera module is warped accordingly and an image surface is curved, and therefore there is concern about deterioration in image capturing. Thus, it is important to suppress warping of the fixed portion in the FPC on which the camera module is mounted.
As a technique for suppressing warpage of an FPC, for example, PTL 1 discloses a technique of suppressing warpage by controlling thermal expansion coefficients of one main surface side and the other main surface side of an FPC to be equal to each other. In addition, for example, PTL 2 discloses a technique of suppressing warpage by forming substantially equal patterns on both sides of a substrate.
On the other hand, a resolution of a camera module increases rapidly. With the increase in the resolution, it is desired to improve accuracy of parts, and there is a demand to accurately adjust a height between an image surface-side lens and a sensor in an assembling process.
As a camera module mounted in a mobile terminal is desired to have a reduced height, the number of components of the camera module has been reduced and the size of the components has been reduced. In order to achieve the height reduction, there is a camera module that has an image surface-side lens arranged immediately above a sensor. When the image surface-side lens is arranged immediately above the sensor, the image surface-side lens is fixed to a board in many cases.